With extruder dies fed by plastic extruders in the manufacture of plastic products, for example profiles, tubes or blown films, the quantity involved in a batch is typically determined by the quantity, specified by weight, of the plastic granulate loaded into the extruder. The manufactured extruded plastic products have a specific weight per meter, so that, from the weight of the plastic material used, the quantity involved in a batch can also be determined according to running meters. Since a plastic extruder draws in a very precise quantity of plastic granulate, determined by weight, per rotation of its screw, the quantity of plastic material specified by weight processed by an extruder can be determined simply by the number of screw rotations. If a manufacturing process for a running batch of the type specified in the introduction, for example in a procedure known from DE 40 27 319 A1, ends when the rotations of the extruder screw corresponding to the batch quantity have been counted, unprocessed plastic granulate is typically still found in the storage and intermediate storage tanks. Should a subsequent batch then be run with a different recipe, that is with another plastic granulate, after the end of the batch, the leftover plastic granulate from the storage tank and the intermediate storage tank must be removed. This material is typically not processed for other batches, but instead discarded.
In the known procedure, it only occurs in exceptional cases that, at the end of a batch, the storage tank or intermediate storage tank has run empty or nearly empty. This is attributable to the fact that the storage tank is provided with a fill level meter, up to which it is always filled with material, for example through a vacuum line, when its discharge opening feeding into the intermediate storage tank is closed. The result is that the storage tank also will always be completely filled at the end of a batch, when the intermediate storage tank has not quite attained its lower fill level, and is filled again through opening of the discharge opening of the storage tank.